Japanese Unexamined Patent Application Publication No. 2002-246244 and Japanese Patent No. 3952971 each disclose a common mode choke coil including three winding coils.
In the common mode choke coil disclosed in Japanese Unexamined Patent Application Publication No. 2002-246244, three wires are wound in a regular manner on a signal input electrode side, and the three wires are wound in an isolated manner on a signal output electrode side.
In the common mode choke coil disclosed in Japanese Patent No. 3952971, a first wire and a second wire are wound around a first layer of a winding core portion, and a third wire is wound around a recessed portion between the first wire and the second wire that are wound around the first layer. This structure enables distances between the centers of any two wires of the three wires to be equal.